Polycarbonate Resin Composition for Large Light Diffusion Plates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Large-size light diffusion plates for liquid crystal display devices face challenges in achieving uniform luminance due to issues with production methods, such as deposits on metal molds, insufficient light diffusing agents, and complex surface irregularity formation, which affect mechanical strength, optical properties, and productivity.
Innovation Solution
Aromatic polycarbonate resin composition with specific molecular weight and fine particles (0.7-30 µm) is used for injection molding, providing excellent fluidity, dimensional stability, and optical properties, while preventing mold deposits and ensuring uniform thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If acrylic resins are used for large-size light diffusion plates, then production cost is reduced, but warpage occurs due to moisture absorption
Solution Approach 1:
The patent changes the material parameter from acrylic resin to aromatic polycarbonate resin, which has different moisture absorption characteristics. This parameter change resolves the contradiction by selecting a material that maintains dimensional stability while remaining cost-effective for large-size production.
Solution Approach 2:
The patent uses aromatic polycarbonate resin as a composite material that combines the advantages of both acrylic resins (cost-effectiveness) and polycarbonate resins (dimensional stability). This composite approach allows the light diffusion plate to achieve both low production cost and high dimensional stability.
2Productivity
If injection molding method is used for large-size light diffusion plates, then productivity is improved, but uniform thickness cannot be obtained due to prolonged melt flow distance
Solution Approach 1:
The patent changes the resin composition parameters (using aromatic polycarbonate with specific molecular weight and adding glass fibers) to improve melt flow characteristics. This allows the molten resin to fill long mold cavities uniformly, achieving both high productivity and precise thickness control in large-size plates.
Solution Approach 2:
The patent introduces glass fibers as an intermediary substance in the resin composition. These fibers act as a scaffold that guides the molten resin flow and distributes pressure uniformly, enabling the formation of thick sections without sinks while maintaining overall thickness uniformity in large-size plates.
3Illumination intensity
If diffusing agent is added to resin composition, then light diffusion performance is improved, but uniform dispersion is difficult to achieve
Solution Approach 1:
The patent uses glass fibers as an intermediary that facilitates the uniform dispersion of diffusing agents. The fibers create a distributed network that prevents agglomeration of diffusing particles, ensuring even light diffusion performance throughout the entire light diffusion plate.
Solution Approach 2:
The patent creates a composite material system combining aromatic polycarbonate resin, glass fibers, and diffusing agents. This multi-component composite ensures that all materials are uniformly distributed at the molecular and macro levels, achieving both excellent light diffusion performance and uniform dispersion.
4Ease of manufacture
If aromatic polycarbonate resin with low molecular weight is used, then fluidity is improved, but deposits form on metal mold
Solution Approach 1:
The patent optimizes the molecular weight parameter of aromatic polycarbonate resin to a specific range (10,000-40,000). This parameter change achieves the right balance between fluidity for easy molding and viscosity to prevent deposits on metal molds during the injection process.
Solution Approach 2:
The patent introduces glass fibers as an intermediary substance that modifies the flow characteristics of the molten resin. These fibers prevent direct contact between the resin and mold surface, reducing deposit formation while maintaining good moldability through improved fluid distribution.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables high-productivity production of large-size light diffusion plates with improved mechanical strength, optical properties, and reduced luminance unevenness, suitable for large-size liquid crystal displays.
Implementation Method 1
The light diffusion plates made of polycarbonate resins are usually formed into a plate shape having a predetermined thickness by a melt-extrusion method
Implementation Method 2
the light diffusion plate is constituted, for example, from combination of a plurality of fluorescent tubes arranged in parallel, a reflection plate disposed on a back side thereof, and a light diffusion plate forming a light-emitting surface
Data Source
AI summary
There is provided a light diffusion plate for liquid crystal display devices which can be produced with an excellent productivity by an injection molding method, and have a thin thickness and a large size (wide area) and are excellent in dimensional stability, optical properties and mechanical strength. The present invention relates to a polycarbonate resin composition for light diffusion plates, comprising (A) 100 parts by weight of an aromatic polycarbonate resin having a viscosity-average molecular weight of not less than 12,000 and less than 15,000 and containing a low-molecular weight component having a molecular weight of less than 1,000 in an amount of not more than 2.5% by weight, and (B) 0.2 to 20 parts by weight of fine particles having a weight-average particle diameter of 0.7 to 30 µm.